Forces in Two Dimensions
Practice Test
1.
To find the magnitude of the resultant vector for two vectors that are at some angle other than 90°, use __________.
a.
the Law of Cosines
b.
R
2
=
A
2
+
B
2
c.
the Pythagorean theorem
d.
R
2
=
A
2
-
B
2
Hint
2.
How do you calculate your weight in newtons?
a.
(9.80 m/s
2
)sin
θ
b.
c.
(9.80 m/s
2
)(
m
)
d.
2π(
m
)
Hint
3.
A tennis ball is dropped from 1.5 m above the ground, touches the ground for 0.008 s and rebounds to a height of 0.75 m. What is the ball's velocity when it hits the ground?
a.
-5.4 m/s
2
b.
3.8 m/s
2
c.
-3.8 m/s
d.
-5.4 m/s
Hint
4.
How long will it take an airplane at rest that accelerates uniformly at 2.5 m/s
2
to reach a ground velocity of 7.0×10
1
m/s that is required for take off?
a.
4 s
b.
11 s
c.
28 s
d.
35 s
Hint
5.
Find the uniform acceleration that causes a car's velocity to change from 27 m/s to 45 m/s in a 6.0-s period.
a.
18.0 m/s
b.
18.0 m/s
2
c.
3.0 m/s
d.
3.0 m/s
2
Hint
6.
When there is no relative motion between two surfaces, the force exerted by one surface on the other is called __________.
a.
resistance
b.
the kinetic force
c.
kinetic friction
d.
the static friction force
Hint
7.
Which of the following represents the Angle of Resultant Vector?
a.
cos
θ
=
R
x
/
R
y
b.
tan
θ
=
R
x
/
R
y
c.
cos
θ
=
R
y
/
R
x
d.
tan
θ
=
R
y
/
R
x
Hint
8.
In Figure 4-16c, if the box has a mass of 6.0 kg, what will the normal force of the table on the box be?
a.
9.8 N
b.
8.8 N
c.
110 N
d.
50 N
Hint
9.
__________ means that equal displacements occur during successive equal time intervals.
a.
Average speed
b.
Uniform acceleration
c.
Uniform motion
d.
Average acceleration
Hint
10.
The slope of the line tangent to the curve on a velocity-time graph at a specific instant of time is the __________.
a.
instantaneous velocity
b.
instantaneous acceleration
c.
average velocity
d.
displacement
Hint
11.
In Figure 4-16b, if the box has a mass of 6.0 kg, what will the normal force of the table on the box be?
a.
160 N
b.
9.8 N
c.
50 N
d.
8.8 N
Hint
12.
For the situation in Figure 4-5a, if
F
1
= 200 N and
F
2
= 500 N, what would
F
net
be?
a.
300 N to the left
b.
700 N to the right
c.
300 N to the right
d.
700 N to the left
Hint
13.
If standing on a scale in an elevator, as in Figure 4-9, and the scale reads 120% of your weight, what is the acceleration of the elevator?
a.
0.8
g
, up
b.
0.2
g
, down
c.
1.2
g
, down
d.
0.2
g
, up
Hint
14.
A sled of mass 40.0 kg is pulled along flat, snow-covered ground. The static friction coefficient is 0.28, and the kinetic friction coefficient is 0.08. What force is needed to keep the sled moving at a constant velocity?
a.
310 N
b.
3900 N
c.
31 N
d.
3.2 N
Hint
15.
A 75-kg swimmer steps off a 10.0-m tower. What is the swimmer's velocity on hitting the water?
a.
-14.0 m/s
b.
38.3 m/s
c.
0.25 m/s
d.
27.1 m/s
Hint
16.
A 225-N weight has one horizontal rope exerting a force of 98.0 N on it. What are the magnitude and direction of the force needed to put the weight into equilibrium?
a.
2.45×10
1
N at 113°
b.
1.27×10
2
N at 113°
c.
2.45×10
2
N at 113°
d.
2.45×10
2
N at 293°
Hint
17.
Looking at Figure 2-20, at what time would the first picture of the joggers be most likely to have occurred?
a.
1 s
b.
0 s
c.
-1 s
d.
it cannot be determined from the given information
Hint
18.
You and a friend leave school at the same time. You drive at a constant 55 km/h and your friend drives 7.0×10
1
km/h. How long does it take each car to reach a mall that is 25 km from the school?
a.
you: 1 hour 40 minutes, your friend 36 minutes
b.
you: 2.2 hours, your friend: 2.8 hours
c.
you: 22 minutes, your friend: 27 minutes
d.
you: 27 minutes, your friend: 22 minutes
Hint
19.
An object that has a force exerted on it is called __________.
a.
static
b.
the agent
c.
the system
d.
the environment
Hint
20.
A 175-N sign is supported in a motionless position by two ropes that each make 53.0° angles with the horizontal. What is the tension in the ropes?
a.
175 N
b.
146 N
c.
109 N
d.
310 N
Hint
